What are some countries that have sparse population densities? What physical factors account for their low populations? In detail please

There might not be much room to live, so there can't be many people there.  

There are only enough resources for a few people

There might be fighting, and people moved away

The place might be hard to reach, and not everyone wants to try.

In rare cases, the place might be restricted to only certain people.

answerinternational border(ib);